The broad research objectives are concerned with investigation of gene(s) for neoplastic transformation in strongly transforming RNA tumor viruses and tumors in animals induced by chemical carcinogens. The specific aims will be directed toward the elucidation of the origin of genes for neoplastic transformation in avian sarcoma viruses and in avian tumor cells, and comparison of the transforming gene sequences from various sources. The method to be used includes: 1) Induction of tumors in avian species with chemical carcinogens, 2) Cultivation of tumor cells in vitro and infection of cells with non-transforming avian leukosis viruses, 3) Isolation of recombinant avian sarcoma virus. 4) An endogenous DNA polymerase reaction and selection of transforming gene specific DNA sequences after hybridization with excess of original avian leukosis virus RNA, and 5) Hybridization of the transforming gene-specific DNA with DNAs of normal and tumor cells of the same individual bird to determine the transforming gene sequences in those cells. Two out of ten white Pekin ducks, implanted with 20-methylcholanthrene intramuscularly, developed lesions approximately one centimeter in diameter located immediately beneath the skin and in the adjacent subcutis and superficial intermuscular fascical area of the left rear limb where the chemical was implanted. The tumor was diagnosed as experimental sarcoma. The cells from this tumor have been growing in vitro sucessfully. The duck tumor cells in culture are being infected with Rous associate viruses 61, 7 and 49. The progeny viruses will be assayed for a recombinant sarcoma virus in c/o chicken cells weekly intervals. BIBLIOGRAPHIC REFERENCES: Kang, C.-Y. 1975. Characterization of endogenous RNA-directed DNA polymerase activity of reticuloendotheliosis viruses. J. Virol. 16:880-886. Kang, C.-Y., T.C. Wong, and K.V. Holmes. 1975. Comparative ultrastructural study of four reticuloendotheliosis viruses. J. Virol. 16:1027-1038.